Previous studies have shown that undifferentiated human embryonic stem cells (hESC) can survive in the brains of laboratory rats with Parkinson's disease. But until now it was unclear whether hESCs can become fully functional members of the host animal's neuronal architecture - a basic necessity if stem cells are ever to be used in medical treatments replenishing missing or damaged neurons in human patients with neurodegenerative diseases such as Parkinson's or Alzheimer's disease.
Now, research at the Salk Institute for Biological Studies indicates for the first time that hESCs mature into fully functional adult brain cells and integrate into the existing nervous system when these human cells are injected in the developing brains of two-week-old mouse embryos. This novel finding paves the way for a new approach to the study of neurodegenerative disorders and has the potential to speed up the testing of therapeutic drugs to treat these diseases.